Deletion mutation of p300 HAT reduced the enhancing effect of p300 on COX-2 expression. (A-B) p300 (A) and COX-2 (B) protein levels in nuclear extracts of ΔHAT- or p300-transduced HFb determined by Western blots. (C-D) COX-2 promoter activities in p300- or ΔHAT-transduced HFb stimulated with or without PMA (C) or with or without IL-1β or LPS (D). (E-F) p300 (E) and COX-2 (F) protein levels in nuclear extracts of RAW 264.7 transduced with ΔHAT or p300. (G) COX-2 promoter activities in transduced RAW 264.7 cells treated with or without LPS. In panels A, B, E, and F, the top panel shows a representative blot and the bottom panel shows mean ± SEM of the densitometry of 3 experiments. Each bar in C, D, and G denotes mean ± SEM of 3 experiments. A mock vector and normal control were included in all experiments with similar results.